Wireless communication technologies such as long-term evolution (LTE), which is a 4th Generation Radio Access Technology, have enabled mobile broadband to become a reality. The increased demand for high data rates is pushing operators for a densification of the macro cell layer as well as the introduction of heterogeneous networks with the addition of a small cell layer using the same frequency as the macro layer. This may lead to increased interference between cells both inside the macro and small cell layers, as well as interference between layers. And with the densification of the macro cell layer and the introduction of the small cell layer, the interference between cells and between users is increased significantly and threatens to limit the user throughput that can be achieved when adding new network equipment.
Some solutions include using different carrier frequencies for the macro layer and the small cell layer, but this drives up costs for operators having to purchase additional wireless communication network bandwidth, i.e., frequency spectrum.
Another solution is resource partitioning between cells. In the time domain, an Almost Blank Subframe (ABS) feature introduces protected subframes where the macro cell does not transmit data and hence allows smaller cells the opportunity to transmit data with little interference, allowing higher modulation levels for greater throughput. ABS, however, reduces the data throughput available by macro cell users.
In the frequency domain, carrier aggregation (CA) allows small cells and macro cells to transmit control signals on different frequencies and use the combined aggregate spectrum for greater throughput. CA, however, relies on an operator having access to multiple carriers.
Inter-cell interference coordination (ICIC) can also be used to limit interference between cells but requires communication between base stations. ICIC includes granular control of channel conditions for user data elements.
User data in a communication network may be grouped into elements referred to as a Physical Resource Block (PRB), which is a segment of both the frequency spectrum and time domain. Although a resource element (RE), which is comprised of a single symbol that is modulated on a single subcarrier (e.g., an LTE symbol is 71.9 μs in length modulated on 15 kHz), is the most granular element in the communication network, network components generally contend with larger collections of REs that span multiple symbols and multiple subcarriers. The PRBs define such larger collections of REs.
A first cell may transmit user data in a PRB at the same time a neighboring second cell transmits user data in the same PRB, which is the exact same set of subcarriers and symbols (time slots). The simultaneous transmission may cause interference between the neighboring cells because the two cells are competing for usage of the same physical resource.
Communication between base stations implementing ICIC allows the base stations to signal between the cells and schedule channel conditions in the cells to avoid such competition for resources and thus, attain higher spectral efficiency. However, ICIC requires constant communication between cells to manage such coordination between cells, and thus, uses a portion of the communication network bandwidth. As such, conventional solutions do not provide a capability of predictably scheduling different power levels for PRBs in a cell.